Unit 1 Flashcards
force that opposes the motion of objects that move through the air
air resistance
the maximum speed an object will reach when falling through a substance, such as air
terminal velocity
describes the fall of an object on which only the force of gravity is acting
free fall
a force that is directed toward the center of a curved or circular path
centripetal force
states that if no external forces act on a group of objects, their total momentum does not change
law of conservation of momentum
a change in an object’s position relative to a reference point
motion
distance and direction of an object’s change in position from the starting point
displacement
distance an object travels per unit of time
speed
the speed and direction of a moving object
velocity
property of a moving object that equals its mass times its velocity
momentum
rate of change of velocity; can be calculated by dividing the change in the velocity by the times it takes the change to occur
acceleration
acceleration of an object toward the center of a curved or circular path
centripetal acceleration
a push or pull exerted on an object
force
sum of all the forces that are acting on an object
net force
force that opposes the motion between two touching surfaces
friction
attractive force between two objects that depends on the masses of the objects and the distance between them
gravity
a region of space in which every point has a physical quantity, such as a force
field
gravitational force exerted on an object
weight
states that an object moving at a constant velocity keeps moving t that velocity unless an unbalanced force acts on it
Newton’s first law of motion
tendency of an object to resist any change in its motion
inertia
states that the acceleration of an object is in the same direction as the net force on the object, and that the acceleration equals the net force divided by its mass
Newton’s second law of motion
states that when one object exerts a force on a second object, the second object exerts a force on the first object that is equal in strength and in the opposite direction
Newton’s third law of motion
When a falling object reaches terminal velocity, the force of gravity _______________ the force of air resistance.
equals
When an object moves in a circular path, the net force is called a ________________.
centripetal force
_______________ is the change in velocity divided by the time needed for the change to occur.
Acceleration
Any change of distance over time is called _______________.
speed
The distance and direction between the final position and the starting position is the _______________.
displacement
Acceleration toward the center of a curved or circular path is called _______________.
centripetal acceleration
An object traveling in a circular path is accelerating because its _______________.
direction changes
Will a thrown ball or a dropped ball hit the ground first when dropped or thrown from the same height?
Both balls hit the ground at the same time.
An object’s momentum includes its _______________.
velocity and mass
The distance between an object and a reference point is the object’s _______________.
position
What is the equation for momentum?
p = mv
_______________ speed is found by dividing total distance traveled by the total time.
Average
_______________ speed is the speed of an object at any instant of time.
Instantaneous
If an object has a constant velocity, then it has an acceleration of ____________.
zero
A change in velocity means a change in _____________________.
speed, direction, or both
Which term best describes the forces on an object with a net force of zero?
balanced forces
How does the gravitational force change as two objects move farther apart?
It decreases.
What is the gravitational force exerted on an object called?
weight
What explains why astronauts seem weightless in orbit?
The spacecraft is in free fall.
